[Qemu-discuss] qemu and vhost-user-gpu

[Gert Wollny]

Hello all, 

now that the vhost-user-gpu patches landed I wanted to try it out but I
got an error message: 

"qemu-system-x86_64: -object vhost-user-
backend,id=vug,cmd=/opt/local/libexec/vhost-user-gpu: object type
'vhost-user-backend' isn't supported by object-add"

The full command line to run qemu is given below, the chunk for vhost-
user-gpu is taken directly from the commit message (only the command
changed to point to the actual executable, but that doesn't seem to
make a difference) 

>>>
VHOST_GPU=/opt/local/libexec/vhost-user-gpu

/opt/local/bin/qemu-system-x86_64 -enable-kvm \
   -smp 5 -M q35 -m 8G \
   -drive format=raw,file=ubuntu-19.04.raw,if=virtio 
   -net nic,model=virtio -net user,hostfwd=tcp::2222-:22 \
   -soundhw hda 
   -object vhost-user-backend,id=vug,cmd=$VHOST_GPU\
   -device vhost-user-vga,vhost-user=vug 
   -fsdev local,id=test_dev,path=$LOCALSHARE,security_model=none \
   -device virtio-9p-pci,fsdev=test_dev,mount_tag=test_mount \
   -display sdl,gl=on
<<<

Qemu was compiled with 

>>>
./configure --disable-git-update \
  --prefix=/opt/local/ \
  --target-list=x86_64-softmmu \
  --enable-kvm \
  --disable-werror \
  --enable-virglrenderer \
  --enable-sdl \
  --enable-attr \
  --enable-membarrier \
  --enable-virtfs \
  --enable-vhost-user
<<<

Before, with version 6 or 7 of the patches I got it somehow running
with spice, but since this was rather cumbersome I hoped that this
would no longer be needed - also I want to be able to switch between
the GLES backend and the GL backend.

Now my questions are: 
  
Is it at all possible to use the SDL backend with vhost-user-gpu or is
spice a requirement? 

If SDL is possible - what could be wrong with my setup?

If SDL is not possible - how can I force a certain GL context type (GL
vs. GLES) or is this not (yet) possible? 

Many thanks, 
Gert